MAWP of Brass Valve

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How do i compute for a minimum allowable thickness of brass valve? We were ask to do some check on a piping system and found out that valves installed were machined (inside diameter) in order to fit to the existing pipeline.

Pump Dischanrge Configuration

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In the attached pic we have got two configurations of pump discharge line, both the configurations provide good amount of flexibility. Can anybody explain under what circumstances these configurations should be used. As it is clearly visible that both have it's own advantages..but one is saving the

Arrangement of Pump and Valves

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Over curiosity, the arrangement pump and valves are- pump, check valve, manual valve following the flow of direction. . This is I believe is the rule of thumb!! However, there are another 5 possibilities of arrangements. What is the consequences if we swap or arrange according to another 5!!

Can’t we all just get long: evolution of altruism edition | Gene Expression

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Samir Okasha is a philosopher of science and author of Evolution and the Levels of Selection. So his recent comment in Nature, Altruism researchers must cooperate, is informed by a scholarly background in these controversies. From what I can gather Okasha’s stance in this case is to “push back” on Nowak & Wilson in particular, who are the ones making positively audacious claims:

All this disagreement creates the impression of a field in massive disarray. In reality, many of the players involved are arguing at cross purposes. Nowak and his colleagues, for instance, have developed a mathematical model that they claim provides a more direct way to calculate the evolutionary dynamics of a social trait such as altruism…However, they overlook the fact that inclusive fitness theory explains what organisms are trying to maximize. It is not just a tool for calculating when a social trait will evolve.

Likewise, in arguing that ecological factors, rather than kinship, are key to the evolution of social-insect colonies, Wilson is imposing a false dichotomy…To fully understand how these colonies evolve, researchers need to consider ecological factors and relatedness. Whether they stress the importance of one over the other will depend on the question they are asking. For example, relatedness has proved crucial to understanding conflicts between the queen and her workers over the production of male versus female offspring in ants, bees and wasps. For questions about how tasks are allocated to the workers in an ant colony or why the size of colonies differs across species, ecological factors are probably more relevant.

As a “big picture” guy Okasha takes a step back, and compares evolutionary biology to physics (not favorably I might add):

Much of the current antagonism could easily be resolved — for example, by researchers situating their work clearly in relation to existing literature; using existing terminology, conceptual frameworks and taxonomic schemes unless there is good reason to invent new ones; and avoiding unjustified claims of novelty or of the superiority of one perspective over another.

It is strange that such basic good practice is being flouted. The existence of equivalent formulations of a theory, or of alternative modelling approaches, does not usually lead to rival camps in science. The Lagrangian and Hamiltonian formulations of classical mechanics, for example, or the wave and matrix formulations of quantum mechanics, tend to be useful for tackling different problems, and physicists switch freely between them.

History shows that, despite its enormous empirical success, evolutionary biology is peculiarly susceptible to controversy and infighting. This is particularly true of social evolution theory, in part because of its potential applications to human behaviour. In the 1970s and 1980s, for instance, left-wing scholars bitterly rejected biological explanations for phenomena such as religion and homosexuality, because they feared such explanations would be used to justify a continuation of existing inequalities.

When evolutionary biologists start to look like macroeconomists from the outside, it’s not a pretty picture.

Natural selection in our time | Gene Expression

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Last month in Nature Reviews Genetics there was a paper, Measuring selection in contemporary human populations, which reviewed data from various surveys in an attempt to adduce the current trajectory of human evolution. The review didn’t find anything revolutionary, but it was interesting to see where we’re at. If you read this weblog you probably accept a priori that it’s highly unlikely that evolution “has stopped” because infant mortality has declined sharply across developed, and developing, nations. Evolution understood as change in gene frequencies will continue because there will be sample variance in the proportions of given alleles from generation to generation. But more interestingly adaptive evolution driven by change in mean values of heritable phenotypes through natural selection will also continue, assuming:

1) There is variance in reproductive fitness

2) That that variance is correlated with a phenotype

3) That those phenotypes are at all heritable. In other words, phenotypic variation tracks genotypic variation

Obviously there is variance in reproductive fitness. Additionally, most people have the intuition that particular traits are correlated with fecundity, whether it be social-cultural identities, or personality characteristics. The main issue is probably #3. It is a robust finding for example that in developed societies the religious tend to have more children than the irreligious. If there is an innate predisposition to religiosity, and there is some research which suggests modest heritability, then all things being equal the population would presumably be shifting toward greater innate predisposition toward religion as time passes. I do believe religiosity is heritable to some extent. More precisely I think there are particular psychological traits which make supernatural claims more plausible for some than others, and, those traits themselves are partially determined by biology. But obviously even if we think that religious inclination is partially heritable in a biological sense, it is also heritable in the familial sense of values passed from one generation to the next, and in a broader cultural context of norms imposed from on high. In other words, when it comes to these sorts of phenotypic analyses we shouldn’t get too carried away with clean genetic logics. In Shall the Religious Inherit the Earth? Eric Kaufmann notes that it is in the most secular nations that the fertility gap between the religious and irreligious is greatest, and therefore selection for religiosity would be strongest in nations such as Sweden, not Saudi Arabia. But as a practical matter biologically driven shifts in trait value in this case pales in comparison to the effect of strong cultural norms for religiosity.

Below are two of the topline tables which show the traits which are currently subject to natural selection. A + sign indicates that there is natural selection for higher values of the trait, and a – sign the inverse. An s indicates stabilizing selection, which tells you that median values have higher fitnesses than the extremes. The number of stars is proportional to statistical significance.


future1

future2

Some of this is not surprising. The age of the onset of menarche has been dropping in much of the world. I suspect this is mostly due to better nutrition, but a consequence of this shift is earlier fertility for some females. The authors are nervous about the robust correlation of higher fertility with lower intelligence, but notice that the pattern for wealth and income is different and more complicated. The key is to look at education. Whether you believe intelligence exists or not in any substantive concrete sense, those who are more intelligent are more likely to have had more education, and there’s a rather common sense reason why investing in more schooling would reduce your fertility: you simply forgo some of your peak reproductive years, especially if you’re female. The higher you go up the educational ladder the stronger the anti-natalist cultural and practical pressures become (the latter is a heavier burden for females because of their biological centrality in child-bearing, but both males and females are subject to the former). As with religion even if the differences have no biological implication because you believe the correlations are spurious or reject the existence of the trait one presumes that parents and subcultures pass on values to offspring. If higher education has anti-natalist correlations we shouldn’t be surprised if subsequent generations turn away from higher education. Their parents were the ones who were more likely to avoid it.

We live in interesting times.